Method of increasing the productiveness of oil-wells.



I. L. DUNN.

METHOD OF INCREASING THE PRODUGTIVENBSS OF OIL WELLS.

APPLICATION FILED APR. 13, 1911.

Patented July 22, 1913.

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imity to the latter.

IRWIN L. DUNN, OF LONGBEACH, CALIFORNIA.

METHOD OF INCREASING THE PRODUCTIVENESS OF OIL-WELLS.

roeases.

Specification of Letters Patent.

Patented July 22,1913.

Application filed April 13, 1911. Serial No. 620,854.

T 0 all whom it may concern Be it known that I, IRWIN L. DUNN, a citizen of the United States, residing at Longbeach, in the county of Los Angeles and State of California, have invented certain new and useful Improvements in Methods of Increasing the Productiveness of OillVells, of which the following is a specification.

It is well known that the productiveness of an oil well diminishes rapidly as its life or period of production is prolonged and that ordinarily at least, the diminution in flow or production is not due to the exhaustion of oil from the sand or rock. Probably various causes contribute to some extent to this result, among others, of which may be mentioned that the pores or cavities and fissures in the oil-bearing sand forming the channels become clogged at their outlets with material transported by the oil, mainly paraffin. It is therefore common practice to shoot the wells which have ceased to produce satisfactorily, that is, to explode charges of high explosive within the well at the level of the oil-bearing stratum, with the result, as it is supposed, that the rock is broken up, the cavity immediately surrounding the well enlarged, and new channels other than those clogged with paraffin, etc., opened for the passage of oil to the well. It is also a well known expedient for the purpose of removing the paraffin, to force heated air, gas, or steam into the well and into the crevices of the rock immediately surrounding it, in the oil-bearing stratum for the purpose of melting the paraffin and so clearing it away for the free flow of oil. Neither of these processes, however, is intended to or does affect the oil-bearing stratum at any considerable distance from the well, their entire function being to open up channels or passages in immediate prox- It is also a matter of common knowledge among those having to do with the production of petroleum, that the stratum of oil-bearing rock lies between substantially impervious strata located above and below the same, the upper impervious stratum being vaulted, as it were, or extended into or meeting walls which close in the oil sand at its edges. The latter fills the space between the adjacent strata, but is very porous and adapted to contain quantities of fluid, whether liquid or gas, such as water, oil, and natural gas, which naturally arrange themselves in the order of their specific gravities. The gas occupying the upper portion of the stratum and usually under great pressure, forces the oil into the wells when any of the latter are drilled to penetrate the oil sand, at the same time working its own way through the stratum and escaping at the wells. Exactly what happens is of course a matter of surmise and can never be absolutely determined, but to the best of my knowledge and belief the pressureof the gas not only acts upon the surface of the oil in the lower levels of the strata to force it into the wells, as the gas in a siphon bottle forces the water into the outlet tube, but also by penetrating through the pores and interstices of the rock, compresses, crowds out and entrains the oil which is contained therein very much as water is contained in a sponge, and drives it to seek a lower level in the bottom of the well. lVhether or not this be the true explanation of the action of the gas, it harmonizes with all the phenomena observed in connection therewith by me, and also with the operation of my process for increasing the productiveness of wells and my theory of the latter is based thereon.

It is noted that the decrease in the pro duction of oil wells follows and to a large extent, as, I believe, depends upon the exhaustion of the pressure of the natural gas, and my invention has for its aim to restore the pressure of gas in the vault or chamber above the oil and in the pores and interstices of the sand filling the same, to a greater or less extent depending upon the particular features of the tract being treated, and the presence of wells, outlets, etc. My process is the same whether the body of oil sand receives a single well or a plurality of wells. In either case it involves forcing a suitable permanent gas or mixture of gases through the wells into the oil stratum where it penetrates the sand or rock in all directions but ultimately rises to the upper levels thereof, though doubtless some portion of the gas or gases, depending on the particular nature or composition of the same, is absorbed either in the oil or in the water beneath the same, or in both. lVhatever happens in this respect, the gas is forced into the well or wells under a considerable pressure which may equal or exceed the original pressure of the natural gas or be but a fraction thereof. But, in any event, the forcing is ordi- 1v carbureted air is put.

narily continued until the required pressure is attained, and may extend over a period of several weeks, months, or even longer. During this forcing operation of course every effort is made to retain the pressure and prevent the gas escaping either at any of the wells or elsewhere.

Ordinarily if there is a deep column of oil in the pump in a well, and resting on the valve thereof, it is sufficient to prevent escape of the gas through this outlet. But if there are open wells sufliciently near to pro vide escape for the gases, and it is to be remembered that the eflect of the pressure may extend hundreds of yards or even miles into the surrounding rock, they should be plugged or filled. Natural gas may be the pressure medium employed or I may use any other permanent gas which may be cheaply manufactured, but preferably I employ air which when forced into and through the rock upon its return not only has the effect of driving out the oil, but also absorbs the lighter hydro-carbons to a greater or less extent, thus becoming an inflammable mixture which may be burned or used for any of the other purposes to which Or, if preferred, the

gasolene or other hydro-carbons contained in the air and which are capable of condensation at ordinary temperatures may be condensed, the air thus forming a convenient source of volatile hydro-carbons. During the period when the air is being driven into the well or wells, they are not pumped nor is the oil withdrawn in any other way. Indeed, the effect of the application of the air pressure while it is applied, is to drive the oil away from the immediate proximity of the well so that pumping or similar operations at the time would be futile. hen, however, the pressure in the rock has reached the required degree, the operation .of the compressors is stopped. The air within the stratum then expands and forces iits way through the porous rock again to the well, driving before it or carrying with it the oil with which the rock is saturated, so that the well receives a supply of oil which in case the pressure is suflicient in l view of the depth of the well, is caused to flow therefrom, or, in the case of less pressure or greater depth of well, the oil accugmulates therein, and may be pumped in the tordinary manner. hen the pressure again falls below what is considered a desirable ipoint, the compressors may be again set at work and the steps of pumping oil and forcing air may be alternated as frequently and for as long a period as is found profitable.

Ordinarily it will be found of advantage at the outset to force the air in for a considerably longer period than will be necessary afterward intermediate the pumping stages. Just how long the forcing of air must be continued and the quantity of air which must be injected depends on local conditions. In some instances, where the bed of oil sand is not very great in extent it is practicable to form the compressed air layer over the entire body thereof. IVhere, however, the sand is of many miles extent, asufficient degree of pressure may be obtained over a desired area of lesser extent, the frictional resistance of the rock or sand to further penetration of the air beyond this area suflicing to maintain the pressure within it. In some cases, where the area is large, the desired pressure may not be obtained within a year, but in others much less time will suf fice.

\Vith this explanation of my process I will proceed to describe an apparatus suitable for carrying out the same, though it will be understood that the particular form of mechanism described is not essential but is one of many which may be employed, and the invention itself is not limited to the precise process described, but the scope thereof is to be gathered from the following claims in which I have set it forth in such terms as to distinguish from the prior art so far as known to me without, however, abandoning or relinquishing any part thereof.

In the drawings forming part of this application, Fig. 1 represents apparatus applied to charge oil-bearing strata with gases from anatural gas well, and Fig. 2, apparatus to charge oil-bearing strata with compressed air. In these views the well is shown in section and broken out to permit of illustrating both the top and the bottom of the well.

The casing 1 is shown extending through the overlying strata 4L to the oil-bearing stratum 3. In the construction shown in Fig. 1, in which natural gas is to be the pressure medium, the well 8 from which it is taken is shown as plugged and provided with a tube extending through the plug and connected by a pipe 7 with the top of the casing of the well to be treated. If, as ordinarily is the case, the pressure of the natural gas is not sufficient, compressors may be introduced in the pipe 7 The casing 1 is closed at the top except for the admission of pipe 7 and the pump tube, which may be of any ordinary construction and which, if filled with oil above the valve to a suflicient height, will prevent the escape of the compressed gas therethrough. In the construction shown in Fig. 2 in which compressed air is the medium employed, a compressor is shown at 9, connected by a pipe 7 with a riser 5 extending into the well and through a plug or packing 2, which closes the well except for said pipe 5 and a pump tube of ordinary construction. In this form the packing maintains the pressure ofthe compressed air in the well.

After the required pressure is obtained the supply of gas or air is shut off and the oil pump is set in motion, and if desired other outlets for the compressed fluid, to permit its escape from the well may be arranged. Ordinarily in the case of natural gas, it is piped away for fuel purposes and in the case of a Well in Which iiill-is used, similar provision may be made, for after it has been forced through the oil-bearing rock, it becomes laden 0r saturated With the lighter hydro-carbons, and highly inflammable; or, if desired, as suggested above, either the natural gas or the ai r nay be treated according to Well known processes, for the purpose of condensing or extracting gasolene and similar hydro-carbons carried thereby.

I claim:

1. A process of operating oil Wells which consists in forcing into the oil-bearing stratum a supply of compressed permanent gas, thereby forming above the oil a body of gas under pressure, and releasing the pressure upon the body of compressed gas at the Well and permitting it to flow therefrom, and collecting the oil from the well.

2. A process of operating oil Wells which consists in forcing into the oil-bearing stratum a supply of compressed permanent gas, thereby forming above the oil a body of gas under pressure and releasing the pressure upon the body of compressed gas at the Well and permitting it to flow thereinto, and pumping the oil from the Well.

In testimony whereof I have hereunto set my hand at Los Angeles, California, this 8th day of April, 1911.

IRWVIN L. DUNN. In presence of- JAMES R. TOWNSEND, L. BnL-LnRIcE.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 0. 

